Continuous gas making process



March 3l, 1936.

CONTINUOUS GAS MAKING PROCESS Filed Aug. 2, 1950 /m l 'S ,4 TToeA/E Ys M. FRNKL 2,035,600

Patented "Man 3l, 1936 UNITED s'rli'lrlas 2,035,609 CONTINUOUS GAS MAKING PROCESS Mathias Frnkl, Augsburg, Germany, assgnor to American Oxythermic Corporation, New York, N. Y., a, corporation of Delaware Application August 2, 1930, Serial No. 472,553

Germany December 2, 1929 9 Claims.

The invention relates to a process for the generation of gas. More particularly, it relates to a process ln which the heat of the generated gas is retained for subsequent augmentation of the gas producing procedure, and includes correlated improvements and discoveries whereby the generation of gas from a fuel material is enhanced. Itis an object of the invention to provide a process for the generation of gas which is char- 10 acterized by an improved heat economy and efflciency, and which may be readily conducted on a commercial scale.

A further object of the invention is to provide a process in which the heat of generated gases will be utilized to effect an increase in temperature of a body of fuel subsequently to be gasified.

Another object of the invention is to provide a processv for the generation of gas in which heat losses are materially decreased,Y and which may be readily operated on a commercial scale.

In the known methods of gasifying coal, coke and similar fuels as heretofore practiced, the gases withdrawn, when dry carbon was being gasied, could not be brought much below 800 C.

This resulted in a 'considerable waste of heatsince for each kilogram of solid carbon in the coal or coke being gasied about 5 cubic meters of gas are generated with a waste heat content of about 1250 Cal.

3o Ine accordance with the present invention, marked heat economy is effected by introducing this greater part of this heat of the withdrawn gases into the layers of fuel in the generator and thus make it available for gasifying the fuel so that the addition of steam may be considerably increased for each kilogram of fuel.

This improved result may be secured according to the present invention by operating with oxygen or air together with steam which is conducted through a generator comprising two shafts or columns united at their bottom ends. In carrying out my invention, steam is introduced alternatingly at the top of a generator column and during passage through glowing fuel effects gasication thereof and then passes through a second column from the bottom toward the top thereof, so that the generated gas gives up its sensible heat to fuel contained in the second column. After a period of time the operation is reversed and the steam is introduced at the top of such second column whose fuel has been preheated by the previous current of gas, and the gas generated in said second column is caused to give up its heat to the fuel in the rst column. The steam cools the column of fuel fromthe top toward the bottom thereof, and at the same time becomes heated to the reaction temperature whereupon it gasies the carbon by reaction therewith.

For a fuller understanding of the nature and objects of the invention reference should be had 5 to the following detailed description taken in connection with the accompanying drawing in which is shown a gas generator consisting of two fuel chambers having a communicating channel at their base adapted for alternate and periodical 10 ow of steam and in which the process of the invention may be effectively carried out.

The steam employed to gasify the fuel is caused to enter the generator alternately at the points a' or a" at the top of the generator columns A 35 or A. The steam travels down the column of fuel which' has previously been heated to incandescence and during its passage through the glowing layers of fuel for example coal or coke effects gasication thereof. The gas then travels 20 through the connecting channel B, passes upwardly through the fuel bed of the other column to which it gives up its sensible heat and nally is drawn 01T at b or b" at a temperature of less than 100 C. l l 25 Air or pure oxygen, or air which has been freed of the greater part of its nitrogen, is introduced .through the valve lc. When operating with oxygen the introduction of such gas is not continuous, for during the rst third of each reversal 30 period the glowing fuel in which has been stored the heat of the previous current of generated gas,

and which has been heated at least at its bottom portion to about 1250 C., contains sufficient heat to react with the steam. It is only when this 35 heat has been used up that oxygen should be introduced as 'otherwise the generator will become too hot during the first few minutes following each reversal. To accomplish such control of the inow of the combustion supporting gas, 40 each generator column is provided with a controller m' or m" which is operative in response to the temperature of the column of glowing fuel column and controls an` oxygen valve o or o which isopened only when the temperature 45 in the generator has fallen below about 800 C. The valves o' and o" are fed by a reversible threeway oxygen valve lp which is actuated together with the steam inlet and. fuel gas outlet valves and is reversed simultaneously therewith, 60 thus cutting off alternately the supply of oxygen to that one of the valves o or o which' is in communication with the generator column which has been heated by the immediately preceding current of generated fuel gas.

The fuel content of the generator column in which the steam, as stated, is introduced from above, becomes cooled from the top toward the bottom thereof, while the'other column, through which the generated gas is conducted on its way to a place of use or storage, becomes heated during this period from the bottom toward the top. After an interval of from five to ten minutes the direction of flow of steam and generated gasesis tor, and that such waste heat is effectively employed to assist in the reaction between the steam and carbon. It will be noted that this quantity of heat, -which is recovered from the escaping generated gases, operates to heat the bed of fuel without causing combustion of any portion of such fuel as is the case when the fuel is heated up by blowing a charge of air therethrough.

The reversing of the currents of steam and gas may be accomplished automatically by means of a servomotor C operated by compressed air. The steam enters alternately at f or f" into the valves g' or g"; the gas leaves the generators alternately at b and b".

Various modifications may be resorted to within the scope of the appendedv claims without departing from the spirit ofthe invention. For example, the columns A' and A may be built as a single generator composed of two columns, or may be considered as two separate generators connected for reverse operation. Also, if desired, the valves b', b" and g', g may be combined into single reversing valves which may be operated to withdraw the generated gases from, or feed steam alternately to one or the other of the columns.

'I'he coal to be gasifled as a rule contains a considerable amount of tar. The tar distils when this coal is heated, but again liquees before leavingthe generator when it contacts with a fresh charge of coal, because it can remain as a vapour only at a temperature higher than 300 C. It is however necessary to remove the tar from the generator while it is in the gaseous state. To this end the blowing time preceding reversal once or twice in about an hour is extended until the gases being withdrawn have attained a temperature of from 400 to 500 C., whereby the tar contained in the fuel is evaporated. More particularly,u in order to remove or vaporize the deposited tar, the passage of steam is continued, for example once every hour, in a given direction through the generator for about iive to ten minutes. Thereby the column through which the outgoing gases are passing will become warmer and the temperature at the outgoing end, or top, will be raised to from 300 to 500 C., which suffices to vaporize the tar- Thus, if steam is passing through shaft A' generating gases therein, and the thus generated gases passing through the channel B and upwardly and out through the shaft A this direction of flow will be continued until the temperature at the top of the shaft A has been raised sufficiently to effect a vaporization of the tar. When the tar has been vaporized from the Shaft A", the flow is reversed and continued in the refuel possesses advantages which are the more noticeable the drier the fuel which is to undergo treatment. A particular advantage resides in that a much greater quantity of steam may be utilized than can be employed in the generators of the more simple type operating with air. This is due to the fact that the recovery of 1250 Cal. p

per kilogram which were previously lost when operating with air and which according to the process of this invention employing an oxygen containing gas are for the greater part 4recovered and made available for gasification, permits an increase in the quantity of steam used from -about 0.4 to about 0.8 kilograms per kilogram of carbon gasified.

I claim:

1. A process for the generationl of gas which comprises forming two columns of coke having a communicating channel at their bases, introducing steam into the top of one of said columns previously heated to reaction temperature whereby gases are generated, passing the gases so generated through the communicating channel and thence `upwardly through the second column of coke, withdrawing the -gases from the top of said second column, alternately and periodically reversing in rapid sequence the Aiow of gases through said coke columns and maintaining the reaction temperature by partial combustion with a gas enriched in oxygen.

2. A process for the generation of gas which comprises charging coke into a gas .generator consisting of two columns in communication-at their base, heating the coke in` at least one of said columns to reaction temperature, introducing steam into the top of said column and conducting the same downwardly through zones of increasing temperature whereby gases are generated, conducting the generated gases to the base of the second column of coke and during such passage introducing thereinto an oxygen containing gas, passing the gaseous mixtureupwardly through the coke in said Second column, wherein it passes toward the top through zones of decreasing temperature, whereby sensible heat of the gases is stored in the coke, and withdrawing the gaseous productA from the top of the second column with alternate and periodical reversal in rapid sequence of flow of the gases.

3. A process for the generation of gas by interaction between a solid fuel and steam which comprises forming two columns of a solid fuel, introducing steam at the top of one of said fuel colwithdrawing the same from the top thereof whereby fuel in said column is preheated by the heat of the generated gases, maintaining the reaction temperature of` the fuel mass by partial combustion with an oxygen containing gas, and alternately and periodically reversing in rapid sequence the introduction of steam with respect to and the flow of gases through said fuel columns,

5. A process for the generation of gas by interaction between a solid fuel and steam which comprises forming two columns of a solid fuel, introducing steam into one of said columns at the top thereof wherein gas is generated by reaction between said fuel and steam, passing the hot generated gases through the other column of fuel wherein heat of said gases is stored and the fuel therein preheated, maintaining said fuel at reaction temperature by partial combustion with an oxygen containing gas, and alternately and periodically reversing in rapid sequence the intraduction of steam with respect to and the ow of gases through said fuel columns.

6. A process for the generation of gas by interaction between a solid fuel and steam in a gas producer having a plurality of shafts and a communicating channel at the base of said shafts, which consists in charging the shafts with coal and operating each'shaft containing coal alternately and periodically in rapid sequence as a gas generator and as a waste heat accumulator whereby sensible heat in generated gases is stored in said coal and utilized to aid the reaction subsequently taking place between said highly heated A i3 viously heated to reaction temperature whereby gases are generated, passing the gases so generated through the communicating channel, in-

troducing a gas enriched in oxygen into the gas stream during passage-through the communicating channel whereby a part of said gas is'burned and thence conducting the hot gases upwardly through the second coal column, withdrawing the gases from the top of said column, alternately and periodically reversing in rapid sequence the introduction of steam into and the flow of gases through said columns of coal, and periodically continuing the withdrawal of gas from a given column until the heatstored therein raises the temperature thereof sufficiently to vaporize deposited tar.

8. A process for the generation of gas which comprises charging solid fuel into a gas generator consisting of two columns in communication at their base, heating the solid fuel in at least one of said columns to reaction temperature, introducing steam'into the top of said column and conducting the same downwardly through zones of increasing temperature whereby gases are generated, conducting the generated gases tothe base of the second column of solid fuel and during such passage introducing thereinto an oxygen containing gas, passing the gaseous mixture upwardly through the solid fuel in said second column, wherein it passes toward the top through zones of decreasing temperature, whereby sensible heat of the gases is stored in the solid fuel, and withdrawing the gaseous product from the top of the second column with alternate and periodical reversal in rapid sequence of the flow of the gases.

9. A process for the generation of gas by interaction between a. solid fuel and steam in a gas producer having a plurality of shafts which comprises charging the shafts with a solid fuel and operating each shaft containing solid fuel alternately and periodically in rapid sequence as a gas generator and as a Waste heat accumulator whereby sensible heat in generated gases is stored in said solid fuel and utilized to aid the reaction subsequently taking place between said highly heated solid fuel and introduced steam in which gases are generated, introducing an oxygen containing gas into one of said columns and at intervals continuing the operation of a given shaft as a waste heat accumulator until the heat stored therein increases the temperature thereof sufliciently to vaporiz'e deposited substances."

.MATHIAS FRANKL. 

